Fluid meter



Jari- 1945- w. M. AHLSTROM EI'AL 2,367,175

FLUID METER Original Filed Aug. 5, 1958 2 Sheets-Sheet 1 4; 1 Z; I INVEIyTORs 2 Sheets-Sheet 2 TORS 71M ATTORNEYS yum/W32;-

w. M. AHLSTROM EIAL Original FiledAug. 5, 1938 2 s 4 Jan. 16, 1945.

Patented Jan. 16, 1945 ,FLUID METER William M. Ahlstrom, Mentor, and Richard J.

Tischler and Frank Harbor, Ohio H. Parsons, Fairport Original application August. .5, 1938, serial No.-

223;284. Divided and this application June 30, I 1941, Serial No. 400,496

, 10 Claims. (01; 73 -202) I l I tion engine and in which this measurement en- This invention relates to fluid measuring means, An object of the invention is to provideimproved fluid measuring. means which willaccu rately measure the flow of fluid throughout a wide range of variation. l I

Another object is to provide an improved flui measuring means which will not materially impede the flow of the fluid which is being measured. a Another object is to provide an improved fluid measuring means which maybe easily manufactured.

Another object is to provide an improved fluid measuring means which may be readily applied to existing fluid conducting-systems.

Another object is to provide an improved fluid measuring means which will magnify variations in fluid pressure. 1 v e Other objects will hereinafter appear."

The invention will be better understood from the description of several practical embodiments thereof, illustrated in the accompanying drawings, in which:

Figure 1 is a diagrammatic illustration of the parts embodying the invention as applied toliquid delivered under a substantially constant head; 1 I

' Figure-2 is a fragmentary sectionalview of a fluid flow responsive apparatus applied to a section of pipe line or similar conduit;

ters into the calculation of mileage per unit quantity of fuel.

While it is intended that the flow devices of this application maybe used in conjunction with such calculating apparatus or other indicating, control, or like devices, such devices are not illustrated, excepting rather generally and diagrammatically, being included vsolely for purposes of completeness of. disclosure and not constituting per se the invention whichit is desired to protect through this application, the terms fiuidmeter, fluid measuring means, and the like, being used to comprehend all such devices.

In Figure 1, a liquid such as gasoline or other fuel is stored in a tank indicated at I, from which it maybe conducted by a pipe 2 to an Figure 3 is an enlarged sectional viewof a portion of the mechanism shown in Figure 1;

Figure 4 is a diagrammatic view of the same apparatus as'shown in Figures 1 and 3 showing it connected to a monometer type -of tube to provide a simplemanner of indicating the flow of fluid; t

Figure 5 is a view similar to Figure 3 showing a modified form of flow device; and

Figure 6 is a diagrammatic-view similar to Figurefl4 showing connections with the device of Figure 5.

This application'is a division of our copending application, Serial Number 223,284, -fi led twine, 1941.

{The above mentioned parent applicationshows one manner inv which fluid measuring devices,

such as constitute the subject matter. of this ap-,-'

plication, may be used in conjunction withcalculating apparatus, and specifically shows a type of apparatus-in which thefluid which is-measir i et elsupplieu to an internal combusugust 5, 1938, now Patent No. 2,250,739, issued auxiliary tank or float chamber 3, the level of the liquid-in the float chamber being eontrolled bya Valve 4 mounted on one end of a pivoted lever, 5, to the other endlof which is; secured a float 6. 1

From the float chamber the liquid may pass through a pipe or conduit 1 to a casing 8, containing a pressure responsive device such as a bellows 9 and an adjustable orifice area controlling valve lll arranged as hereinafter described, thefluid passing from the exterior of the bellows to its'interior, and thence through a pipe or conduit II to its point of delivery, such for instance as theengine, it'being connected in conventional manner to the carburetor, or the like, thereof.

The bellows 9 and valve l0 are so adjusted that the pressure differential between inlet and outlet of-casing 8 is directly proportional to the volume flowing through the conduit ll per unit time, as will be more fully pointed out in the descriptions of Figures 3 and 5.

Conduit H has connected thereto an upwardly extending pipe or conduit I2 which is expanded at l3 into a chamber at about the level of the liquid in float chamber 3, and which serves to prevent surging of the liquid upwardly through conduit l2.

At the upper end of conduit I2 is provided a pressureresponsive device shown' as a bellows l4 connected by a flexible band IE to a drum It fixed on a shaft carrying a pointer or indicator l8.

A substantially constant gravitational head or pressure ismaintai'ned upon the liquid in fluid at very light loads.

elevation above the pipe I I through which the liquid is drawn to its point of delivery. I

As greater demand is placed upon the delivery of liquid, as by a greater suction such as that due to a higher engine speed or wider open throttle, the suction will be imposed upon the liquid contents of pipe II, and being transmitted through pipe l2 to bellows I4, cause the bellows to collapse in proportion to the suction, rotating the shaft I'I through connection IE and moving pointer l8.

It is important that the movement of the head of bellows I4 be in exact and direct proportion to the flow of liquid through pipe II, and, inasmuch as the flow through a fixed orifice is not directly proportional to the difference in pressure existing on both sides, it is necessary to provide a passage for the liquid which will vary in crosssectional area in such a manner that the flow through pipe II will be directly proportional to the pressure or suction existing in this pipe.

It is also essential that differences inthe flow be accurately reflected in the pressure in pipes II and I2 throughout a range covering the entire operability of the device, and particularly with previous devices is it diflicult to maintain-this accuracy when very small quantities of liquid are passing, as when the engine is idling or operating To overcome these difficulties, there is provided a device having an orifice of variable area, together with means for automatically varying the area, so that the pressure in pipes I! and I2 is at all times directly proportional to the amount of liquid passingthrough pipe I I.

In the embodiment illustrated in Figures 1 and 3, there is provided Within the casing 8 a'bellows 9, the interior of which communicates with pipe II. Fluid is permitted to pass to the interior of the bellows through a bushing I9 sealed about a perforation shown as in alignment with the end of pipe II, and extending into this bushing is the end of an orifice restricting member or'spaced plug in shown as of tapering, generally conical shape, and somewhat more acute than the surrounding conical aperture of bushing l9.

The plug has a threaded shank 20 threaded into a boss 2 I, welded or brazed to the casing 8, which is also externally threaded to receive a packing gland 22.

The p of course, may be readily rotated to adjust it axially with respect to bushing l9, bye knurled or similar head 23.

A leafspring 24 is securediby means of a screw 25 and bracket 26 to the casing. and has its end forked to enter an annular recess 21 formed'in bushing I9, and arranged to move this bushingin the direction of the plu opposing the pressure of the liquid surrounding the bellows 9 andinside the casing 8.

It will be apparent that, as the suction of pipe II increases, the walls of bellows 9 tend to col.- lapse and to move the bushing I9 to the left (as seen in Figure 1) increasing the conical-annular space between the interior of thebushin and'the plug, and thus permitting a larger cross sectional stream of liquid to pass to the interior of the bellows and to the pipe II It will be understood that to obtain this vresult the strength of spring 24, together with the pressure exerted by the walls of the bellows itself, must be carefully calibrated, and that the orifice of bushing I9 and thepoint of the plug I.0;must

be so designed that the area of the annular opening between them is always equal to (Where F is the. flow measured in units of volume per unit of time, G is the acceleration due to gravity, and H is the pressure differential between pipes I and II).

In Figure 4, pipe I is shown as provided with abranch 28 which does not appear in Figure 1. This is necessary when the device is to be used in situations where there is not a constant and known head orpressure upon the liquid entering through pipe I and one manner of its use is diagrammatically indicated in Figure 4.

From this figure, it is apparent that pipes I2 and 28 may'have connected between them a U- tube 29, partially filled with mercury or other heavy liquid .30, and the difference in heighth of the level of the liquid in the two arms .of the U will be an indication of the difference in pressure existing in pipes 1 and II.

Inasmuch as' the proportions of the orifice bushing l9 and plug I0 have been so chosen that this difference in pressure is directly proportional to the flow of fluid through the orifice, the heighth of the fluid 30 at one leg of the U tube over that in the other directly tells the rate of flow.

It will be appreciated that the return pipe 28 can be omitted from apparatus such as shown in Figure 1 because its place is taken by atmospheric pressure which exerts itself equally upon the surface of the liquid in tank 3 and upon the exterior of bellows I4. l

Figure 5 shows another form of liquid-flow pressure-controlling device, in which the orifice controlling the flow of fluid is made in the form of a venturi I I9 constituting the end of the liquid discharge pipe III, while into the throat of the venturi projects a tapered valve-like member or plug IIO carried by a bellows I09, to which it is agtlached by means of an annularly grooved boss The tapered plug causes the area of the Venturi throat to vary automatically, so that the pressure difierential from the throat to either end of the venturi is directly proportional to the flow of the fluid through the tubes I07 and This form of device has an added advantage in that the velocity energy imparted to the fluid du-ringits approach to the Venturi throat is re gainedin its travel from the throat to the outlet,

sectional area of the throat varies as the v 2GH the pressure differential from the throat to either the inlet or outlet varies directly with the flow.

The bellows I09 is enclosed within a casing I08 and is assisted in remaining in expanded position bye-spring I24 attached by a screw I25 to a bracket I26 fastened to the interior of the casing. Liquid enters through supplypipe I01.

Pressure within the bellows I09 and at the throat of the venturi is equalized by a bypassliketube I02. Anothertube I03 fromthe pipe I02 extends to the pressure responsive device and the dial actuating mechanism of the instrument.

"The above described parts are all that are necessary where fluid is supplied at a fixed head, asillustrated in Figure 1. p" 1 I 1 t However, when the head of thesupply varies, a tube I04 is connected with the supplyline III, at either end or beyond the Venturi I I9, and a pressure indicating device, such as the. U tube I29 filledwith mercury 130, is connected between tubes I03 and I04, as shown in Figure 6.

The difference of the level of thefluid will, as: in the first embodiment, Joe-directly -proportional to the flow of liquid through conduits III and I01, with the parts proportioned as above described. I w I a In Figure 2, an application'of a device suchas shown in Figures 5 to 6 to alarge conduit is illustrated:

Thez parts are similar to those just described with tubes I03 and I04 leading'to'the indicating part-of the instrument,'but tube I01 is new con.-

- nected through a valve I3I. to one side fo a larger conduit I32 in which'is placed a larger venturi I33 and the tube III ,is'connectedtothe throat I34 of this Venturi through'a. valve I35.

. Of course, it will be apparent that the device of Figure 2 may be used to actuate'any desired or known type of instrument by which the flow of liquid may be determined, or by vwhi'chan apparatusmay be controlled in accordancewith cordance with the -flowof fluid whether used'to' indicate or record this-flow or to control or actuate other apparatus or devices.

This'arrangement' is an improvement over any other known method, in that the head for operating the indicating or recording instrument is many times greater than that due'solely to, and also varies directly with, the flow. The fluid flowing through the Venturi produces a velocity head between I32 and I34 which is proportional to the square of the flow, while the flow of fluid through the bypass-I01 and" III "varies as the square root of the differential. Therefore the flow through the bypass, and that is through the measuring device, varies in direct proportion to '50 of, the actuator having one part fixed with respect the flow of the fluid in the mainconduit.

Inthi'sdevice the operationis based upon the theory that the ratio'of the fiow in conduit I32 to that in conduits I01 and lll'b'ein'gconnected in parallel, is'constant for all the heads or pressure differences, irrespective of 1 the resistance of the conduits.

When used] As the .device shunted around the main conduit. gives -an increase'd head, a larger Venturi throatorbrifice-plate may be used in the main line, .whichgin 't'urn, reduces line losses of the main conduit. .If a agreater, head than that obtainable with the apparatus of Figure 2 is desired, one or more additional Venturi tubes may be interposed between the main conduit and the measuring device, each being connected to its preceding Venturi as is the Venturi of the measuring device shown in Figure 2, that isbetween the throat and one end ofthe' preceding Venturi, and the pressure differentials thus can be automatically magnified to-any desired degree.

' While we have described the illustrated embodiments'of our invention in some particularity,

obviously many others will readily'occur to those skilled 'in' this artfiand we do not, therefore, limit-ourselves to the precise details shown and described,-but'claim as our invention all embodiments, variations and modifications thereof comi'ng'within the scope of the appended claims.

1. A fluid 'meter'comprising a main conduit provided with an orifice, a by-pass around the orifice, anenclosed chamber in said by-pass, a venturi at said chamber, a, tapered orifice controlling member'projecting into the throat of said Venturi, a pressure responsive actuator enclosed in said chamber and having one side in communication with the throat of said Venturi and the other side in communication with one, endfthereof, the

them relatively and being designed to vary the pressure difierential between the throat and one end-of the Venturi in predetermined relation to the "rate of' flow of fluid in the main conduit.

:2. A fluid meter comprising a main conduit provided with a Venturi, a by-pass between one end andthe throat of said Venturi, an enclosed chain-her in said by-pass, a second Venturi at said chamber, a tapered orifice controlling member projecting intothe throat of said second'venturi, a-pressure responsive actuator enclosed in said chamber and having one side in communication with the throat of said second Venturi and the other side in communication with one end thereto said orifice controlling member and having another part fixed with respect to said second Venturi to move them relatively and being designed to vary the pressure differential between the throat and one end of the second Venturi in predetermined relation to the rate of fiow 'of fluid inthe main conduit.

By this-means a greatly increased head can I be obtained for operating the measuring device over that which could be obtained directly from a Venturi or orifice plate in main line I32.

This increased head varies directly with the flow in the main conduit, and both this factv and the greater power obtainable make for ease of calibration and operation of vtheindicating instrument, as well as for the ability to use uniform scale markings on such an'instr'ument.

The accuracy of the instrument is maintained throughout its entire range and a much less complicated apparatus is required than is used with present methods of measuring head.

3. A fluid meter comprising a member having an orifice through which the fluid may flow, an orifice area varying member projecting into said orifice, means'for moving said members relatively and actuated by the pressure differential of the fluid passing through the orifice,,the orifice and orifice controlling member being so designed that the space between them is at all times expressed by the formula J a- 2g'I where a is the area through which fluid may flow at the orifice, F is the fiow measured in units of volume per unit of time, Q is the acceleration due to gravity, and H is the pressure differential.

4. A fluid meter comprising a member having an orifice through whichthe fluid 'may'flow, a tapered orifice area controlling'member extending into the orifice substantially centrally thereof, means for moving said members relatively and actuated by the pressure difierentialottheifluid passing through the orifice, theorifice and orifice controlling member being so designed that the space between them is at all times iexpressedby the formula where a is the area through which fluid may flow at the orifice, F is the flow measured in units of volume per unit of time, 9 is theaoceleration'due to'gravity, and H is the; pressure difierential.

5. A fluid meter comprising -acasing, inlet and outlet conduits connected therewith, a :pressure responsive actuator enclosed-in the casing and supported thereby, a'member provided with an orifice, the, actuator being subjected .to the differential pressures created by flow throughthe' orifice, a tapered orifice area varying member extending into the orifice substantially centrally thereof, one of said members being flxed to and carried by the casing, and the other fixed to and carried by the pressure responsive-actuator whereby they may be moved relatively, the orifice and orifice area controlling member being designed that the space between them is at:all=.times expressed by the formula W a: m

where a is the area through which fluid may flow at the orifice, F is the flow measured in units of volume per unit of time, g is the acceleration due to gravity, and H is the pressure differential.

6. A fluid meter comprising a :sealed casing constituting a part of a conduit through which fluid may pass and a Venturi associated therewith, a Venturi throat restricting member ,projecting into the venturi, a flexible bellows entirely enclosed within the casing and exposed on one side to the pressure of fluid at one end of the Venturi and at its other side to thepressure of fluid at the throat of the venturi oneaend of the bellows being fixed with respect .to the Venturi and its other end being fixed withyrespect to the throat restricting member causing relative motion between the Venturi and throat restricting member which permits the passage of fluid at a velocity head in predetermined relation to its flow.

7. A fluid meter comprising a main conduit, a Venturi therein, a by-pass connected to the conduit at a point external the Venturi and at the throat of the venturi, a sealed :enclosure and a second Venturi constituting apart of :said bypass, a member movable into said second imentioned Venturi and restricting the space therein, and fluid pressure responsive means within the enclosurehaving one side exposed to fluid at the end of the second venturi and 'its other side exposed to fluid at the throat of the second venturi, said pressure responsive means being connected to'the second venturi and to the mem ber to move them relatively and control the velocity head in predetermined relation to the flow.

8. Arfluidmeter comprising a sealed enclosure constltutingra part of the conduit through'which the fluid :mayzflow and a venturi, a restricting member projecting :therein, fluid supply means supplying fluid at a predetermined head to one end of the venturi, pressure responsive means within the enclosure and having one part stationary with respect to the Venturi and another fixed to the 'restricing member and exposed to the pressure of fluid at the throat of the venturi whereby the pressure responsive meansmoves the Venturi and restricting member relatively to maintain the .flow of fluid through the Venturi in accordance with apredetermined function of the pressure at the Venturi throat.

9. 1A fluid meter comprising a venturi, a Venturi throat area varying means, and a pressure responsive :actuator having two relatively movable parts, one of said actuator parts being fixed relativethe yenturi and the other said actuator part being-fixed relative the'throat area varying means .to move the Venturi and throat area varying means relatively,the actuator being directly actuated by the pressure differential between the throat and one-end of the Venturi; the throat area varying means being designed to vary the Venturi throat area 'to maintain the pressure differential in direct proportion to the flow offluid through the venturi.

10. A fluidmeter comprising a conduit including an enclosure, a venturi, a V enturi throat area varying means, and a pressure responsive actuator enclosed within the enclosure and exposed only to the fluid passing through the meter, there being aconnection between the fluid at one side of the actuator and the throat of the venturi and the other side of the actuator being subjected to thepressure at one end of the venturi, the actuator having one part fixed with respect to said Venturi and having another part fixed with respect to said Venturi throat area varying means tomove them relatively, the throat area varyingmeans being designed to vary-the area of the Venturi throat to maintain the pressure differential in direct proportion to the flow of fluid through the venturi, and an indicating device actuated by the pressure difierential having communication with fluid at the throat of the Venturi and communication with fluid at one end of theventuri.

WILLIAM M. AHLS'IROM. RICHARD J. 'I'ISCHLER. FRANK H. PARSONS. 

